Creating a Verification Code (VC) or Security Code (SC)

Providing VC/SC in your web forms will ensure that no other external programs will try to enter or mess up with your website applications. VC/SC is an anti-spammers/bots/robots solution. Some of the special portions of your website that will require VC/SC are: a. Registration Form b. Contact Form, and c. Tell-a-friend Form d. Other forms that request input from users/guests which do not require a registration must also have this. Let's eliminate spammers and bots using my examples below: I used OO PHP, PHP GD Library, OO JavaScript, AHAH (Asynchronous HTML And HTTP), JQUERY 1. Simple Mathematical Expression This is my favorite solution. By providing two random numbers to be added.
code
GET another Expression
=
2. Series of Random Alpha-numeric characters
    By providing a random combination of "upper and lower case alphabets" and numbers.
code
GET another Code Case-sensitive
is
3. Drawing Lines on Code
    Randomize and draw lines to cloak readable characters.
code
GET another Code Case-sensitive
is
SUMMARY:
You can load and use your own fonts, but just make sure fonts are not easily
read or interpreted by OCR (Optical Character Recognition) programs which most robots use.

Secure your codes both client and server sides.
You may expand the idea behind these examples. Explore, understand, imagine, and build your own.